Phthalates

Phthalates are often used as plasticisers for polyvinyl, polyvinyl chloride or cellulose resins. They are esters of phthalic acid. The absorption maxima of diethylphthalate, dibutylphthalate and butylbenzylphthalate are around 275 nm (Fig. 64). 

Phthalates, the di-esters of o-phthalic acid, are ubiquitous in the environment. They are used as plasticisers in different kinds of plastics. One of the most widespread phthalates, di-(2-ethylhexyl)-phthalate or DEHP, occurs in the list of priority pollutants (Annex X) of the Water Framework Directive of the European Union. In the coming years measures have to be taken to reduce discharges, emissions and losses of DEHP into the environment. 

Due to the widespread use phthalates can be found everywhere, not only in soil but also in the laboratory environment, in the usual packing materials for samples and also in solvents. Controlling and reducing the blank values therefore is the main problem in the determination of phthalates. 

With the exception of dimethyl-, diethyl- and dipropylphthalate, all the other phthalates can be considered as being non-polar. They can be easily extracted with a method for non-polar compounds. The recovery of dimethyl-, diethyl-and dipropylphthalate will be poor, because they will be partly removed during clean-up. If these compounds have to be analysed, an extraction as described for herbicides will be more effective. Phthalates tend to adsorb on glass surfaces if they are dissolved in non-polar solvents. Great care should be taken that phthalates are neither introduced nor lost during the determination. 

Although electron capture detection is sufficiently sensitive for phthalates, the preferred method of determination is GC-MS. Phthalates give easily recognised mass spectra with the exception of dimethylphthalate all phthalates show the characteristic fragment ion with m/z 149 as the base peak. 

There is no standardised method for the determination of phthalates in the soil. Currently, a standard for the determination of selected phthalates in water (ISO/DIS 18856 (2002)) is in preparation within ISO/TC 147 - Water Quality. 

Phthalates are a group of chemicals most commonly used to soften PVC (the plastic polyvinyl chloride). In the textile industry they are used in artificial leather, rubber and PVC and in some dyes. There are substantial concerns about the toxicity of phthalates such as DEHP (Bis (2-ethylhexyl) phthalate), which is reprotoxic in mammals, as it can interfere with development of the testes in early life. The phthalates DEHP and DBP (Dibutyl phthalate) are classed as toxic to reproduction in Europe and their use is restricted. Under EU REACH legislation, the phthalates DEHP, BBP (Benzyl butyl phthalate) and DBP are due to be banned by 2015. 

The assumption that all phthalates detected in the body are sourced from vinyl products does not appear to be the case. Alternative sources appear to be cosmetics, detergents, oils and solvents (253, 262). 

Much of the data generated has been as a result of advances in trace analysis in different environments, linked to a lack of understanding between hazard and risk (probability of intrinsic hazard causing an effect). 

The main phthalates under investigation are butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), di-2-ethyl hexyl phthalate (DEHP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP). These investigations include EU risk assessments based on sound science but the political positions on flexible PVC and phthalates cannot be ignored. 

Hundreds of studies have been carried out on phthalates and there are regular updates on the regulatory position (90, 100). The current position is available on the website of the European Council for Plasticisers and Intermediates (ECPI) (www.ecpi.org). 

the most commonly used plasticiser in soft toys and items intended to be put into children s mouths, has had a positive EU and USA (Consumer Product Safety Commission) risk assessment, provided that recommended migration limits have been adhered to (7, 247). However an EU temporary ban on the use of phthalates, in toys and babycare items intended to be put into the mouth by children under three years old, has been renewed on a regular basis since December 1999 until the date of compiling this report. 

There are three isomeric forms of phthalic acids and as many phthalates as shown below  

Out of these three groups, phthalates, which are esters of ortho-phthalic acid, are popular (in fact, they constitute about 80% of all plasticizers used). Esters of two other acids are seldom used because of the higher prices of these acids. 

Main alcohols used in commercial products methyt ethyt butyl, isobutyl, hexyl, cyclohexyl, hep-tyl, octyt 2-ethylhexyl, l-methyUieptyl, butoxycar-bonyhnethyt nonyl, isononyl, decyl, isodecyl, undecyl, tridecyl, benzyl, mixtures of alcohols (e.g., C7 to Cg or Cg to C, etc.), 2,2,4-trimethyl-l,3-pen-tanediol-1 -isobutyrate  

Highly recommended for these polymers PVC, CA, CN, PVAc, PU, EC, EPDM, PMMA, PS, acrylics, cellophane, nitrocellulose, natural synthetic rubber, chlorinated rabber, polysulfide  

Outstanding property compatibility, cost effectiveness, good dielectric properties, UV thermal stability, a broad range of properties, good balance of properties  

Consequently, taking accoimt of all the performance and economic restrictions, the great majority of plasticisers are high-boiling esters, with one type (the phthalates) holding between 85 and 90% of the PVC plasticiser market by volume. Attempts to popularise replacements for phthalates have made limited progress. 

The chemical structure of phthalates is such that they tend to be divided into linear and branched side chain types. In practice, however, all the most widely used phthalates are the branched type. They include di-2-ethylhexyl phthalate (DEHP), also known as dioctyl phthalate (DOP), and two higher molecular weight varieties, di-isononyl phthalate (DINP), and di-isodecyl phthalate (DIDP). They are all general-purpose plasticisers and account for well over half of all the plasticiser usage in Europe. Within this group, the trend in Europe has been towards the American practice, away from DEHP towards DINP and DIDP, because of lower volatility, greater permanence, superior product performance (superior heat and low temperature resistance) and better environmental reputation, and also because of changes in feedstock availability. 

Diethylhexyl phthalate Most widely used good gelling, relatively non-volatile 

Esters of adipic and sebacic acid Diisodecyl adipate (DIDA) 

Good non-volatile behaviour and good low-temperature properties 

Good low-temperature resistance (to -3()°C) and long-term heat resistance (100°C) addition of 0.05% bisphenol A prevents splitting of oxoalcohol ester plasticizers under heat stress 

Outstanding heat resistance, good electrical properties, weather resistance, flameproof not resistant to low temperatures should not be used for products in contact with the skin. Other phosphates have lower resistance to heat 

---

Succinate, benzoate, phthalate and cinnamate give buff or brownish coloured precipitates of the basic ferric salts in the cold. Add dil. H2SO4. The basic ferric succinate dissolves giving a clear solution the other basic ferric salts also dissolve, but simultaneously a white precipitate of the free acid is also formed. 

Phthalein reaction. Fuse together carefully in a dry test-tube a few crystals of phthalic acid or of a phthalate and an equal quantity of ph tol moistened with 2 drops of cone. H2SO4. Cool, dissolve in water and add NaOH solution in excess the bright red colour of phenolphthalein in alkaline solution is produced. 

As a general guide, however, it may be noted that the following have fairly easily recognisable odours methyl and ethyl formate methyl and ethyl acetate (apples) methyl and ethyl benzoate methyl salicylate (oil of winter-green) and ethyl salicylate methyl and ethyl cinnamate. (It is however usually impracticable to distinguish by odour alone between the methyl and ethyl esters of a particular acid.) Methyl and ethyl o. alate, and methyl and ethyl phthalate are almost odourless. Succinic and tartaric esters have faint odours. 

The following liquids may be used (boiling points are given in parentheses) — chlorobenzene (132-3°) bromobenzene (155°) p cymene (176°) o-dichloro-benzene (180°) aniline (184°) methyl benzoate (200°) teti-alin (207°) ethyl benzoate (212°) 1 2 4-trichlorobenzene (213°) iaopropyl benzoate (218°) methyl salicylate (223°) n-propyl benzoate (231°) diethyleneglycol (244°) n-butyl benzoate (250°) diphenyl (255°) diphenyl ether (259°) dimethyl phth ate (282°) diethyl phthalate (296°) diphenylamine (302°) benzophenone (305)° benzyl benzoate (316°). 

The commercial form of Cartesian manostat, model 7A, is depicted in Fig. II, 23, 7 it is normally charged with mercury except for very low pressures when di-w-butyl phthalate is employed. The manostat is highly sensitive in its action furthermore, once the pressure has been set in the instrument, the system may be shut down without disturbing the setting. 

If, however, the sodium hydroxide is removed by allowing it to react with excess of an ester of high boiling point, such as ethyl succinate or ethyl phthalate, super-dry ethyl alcohol may be obtained ... 

If the perfectly anhydrous alcohols are required, the redistilled alcohol may be treated with the appropriate alkyl phthalate or succinate as already detaUed under Ethyl alcohol (5). 

Phthalic anhydride reacts similarly, but the acid phthalates are somewhat more difficult to isolate and the melting points are considerably lower. 

Successful results have been obtained (Renfrew and Chaney, 1946) with ethyl formate methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl and iso-amyl acetat ethyleneglycol diacetate ethyl monochloro- and trichloro-acetates methyl, n-propyl, n-octyl and n-dodecyl propionates ethyl butyrate n-butyl and n-amyl valerates ethyl laurate ethyl lactate ethyl acetoacetate diethyl carbonate dimethyl and diethyl oxalates diethyl malonate diethyl adipate di-n-butyl tartrate ethyl phenylacetate methyl and ethyl benzoates methyl and ethyl salicylates diethyl and di-n-butyl phthalates. The method fails for vinyl acetate, ieri.-butyl acetate, n-octadecyl propionate, ethyl and >i-butyl stearate, phenyl, benzyl- and guaicol-acetate, methyl and ethyl cinnamate, diethyl sulphate and ethyl p-aminobenzoate. 

MC.-Octyl alcohol methyl n-hexyl carbinol CH3CH(OH)(CHj)jCH3 = CgH,OH is converted by heating with phthalic anhydride into sec.-octyl hydrogen phthalate ... 

The latter upon decomposition with dilute hydrochloric acid yields laevo sec.-octyl hydrogen phthalate the crystalline brucine salt, when similarly treated, affords the dextro sec.-octyl hydrogen phthalate. These are reerystallised and separately hydrolysed with sodium hydroxide solution to yield pure I- and d-sec.-octyl alcohols ... 

Introduce 197 g. of anhydrous brucine or 215 g. of the air-dried dihydrate (4) into a warm solution of 139 g. of dZ-acc.-octyl hj drogen phthalate in 300 ml. of acetone and warm the mixture vmder reflux on a water bath until the solution is clear. Upon cooling, the brucine salt (dA, IB) separates as a crystalline solid. Filter this off on a sintered glass funnel, press it well to remove mother liquor, and wash it in the funnel with 125 ml. of acetone. Set the combined filtrate and washings (W) aside. Cover the crystals with acetone and add, slowly and with stirriug, a slight excess (to Congo red) of dilute hydrochloric acid (1 1 by volume about 60 ml.) if the solution becomes turbid before the introduction of... 

Concentrate the combined filtrate and washings (W) to about half the original volume, and pour it into sUghtly more than the calculated amount of dilute hydrochloric acid (use a mixture of 30 ml. of concentrated hydrochloric acid and 30 ml. of ice-water) then add about 300 ml. of water. Collect the active aec.-octyl hydrogen phthalate (crude lA) as above (5). The weight of the air-dried ester is about half that of the dl-ester originally used (7). 

Crystallise the two lots of crude active aec. -octyl hydrogen phthalates separately twice from 90 per cent, acetic acid use 2 g. of acetic acid to each gram of soUd. The recrystaUised esters, if optically pure (8), will melt sharply at 75° if the melting points are below 75°, further recrystallisation is necessary. The yields of optically pure products, m.p. 75°, are 48 g. and 49 g. respectively. 

The yields from the acc.-octyl hydrogen phthalates are almost quantitative. Notes. 

The inactive aec.-octyl hydrogen phthalate may be recrystallised from light petroleum, b.p. 60-80°, or from glacial acetic acid, and then melts at 55°. 

Dlnltro-benzoate p-NItro- benzoate Phenyl- urethane a-Naph- thyl- urethane Hydrogen 3-nltro- phthalate Other Derivatives... 

Indanedioiie (III) may also be prepared by condensation of diethyl phthalate (V) with ethyl acetate in the presence of sodium ethoxide the resulting sodium 1 3-indanedione-2-carboxylic ester (VI) upon warming with sulphuric acid yields (HI). 

---